Marijuana legalization is often touted as a sure route to ending racial disparities in pot-related arrests. But a just-released study indicates that African Americans in legalization states continue to endure marijuana arrests at a higher rate than people of other races.

Mike Males, a senior research fellow at the Center on Juvenile and Criminal Justice, compared marijuana arrest data from before and after the 2012 legalization of recreational marijuana in Colorado and Washington. Arrest rates tumbled in both states from 2008 to 2014, dropping by 90 percent in Washington and 60 percent in Colorado.

But the racial disparity in arrests didn’t budge. In both states the post-legalization arrest rate for blacks was just over double that for non-blacks, just as it was before legalization.

“I am surprised and disappointed by this,” Males said. “The forces that contribute to racial disparities under prohibition are clearly still in place after legalization.”

The study overturns the widely-believed hypothesis that making marijuana illegal contributes to racial disparities in arrest rates. At the same time, racial disparities are imperfect indicators of how a policy affects members of minority groups.

For example, if an enforcement crackdown leads to marijuana arrest rates doubling for blacks and tripling for everyone else, the racial disparity would be smaller but in absolute terms far more blacks would be enduring arrest.

Because African Americans constituted such a disproportionately large proportion of marijuana arrestees prior to legalization, the disparity staying constant during a massive drop in the number of marijuana arrests by definition means that the avoided arrests were also disproportionately African American.

As Males put it, “I wish the disparity were gone, but having such a huge drop in the number of African Americans being arrested is still a good thing”.